Phase IIb Randomized, Double‑Blind, Dose‑Ranging Study of Subcutaneous GIA632 for Facial Repigmentation in Adults with Non‑segmental Vitiligo

Primary objective: To define the dose‑response relationship of GIA632 and to assess its efficacy versus placebo in achieving facial repigmentation at Week 24, measured as the percentage change from baseline in Facial Vitiligo Area Scoring Index (F‑VASI) in adults with non‑segmental vitiligo. This endpoint directly addresses the clinical need for quantifiable improvement of facial lesions, which are most visible and impact patient self‑image. Secondary objectives:

• Estimate the dose‑response and efficacy of targeted doses versus placebo for achieving an F‑VASI75 response at Week 24.
• Determine the dose‑response and treatment effect on total skin repigmentation at Week 24, expressed as percentage change from baseline in Total Vitiligo Area Scoring Index (T‑VASI).
• Assess the dose‑response and treatment effect on total skin repigmentation at Week 24 using the T‑VASI50 response criterion.
• Evaluate the longitudinal efficacy of GIA632 versus placebo on skin repigmentation over the study period.
• Compare GIA632 and placebo at Weeks 12, 24, 36, and 48 using the Vitiligo Noticeability Scale (VNS) score.
• Assess safety and tolerability of GIA632 throughout the trial.

The study enrolled 130 participants who were adults (≥ 18 years) of any gender, all diagnosed with non-segmental vitiligo confirmed by physical examination. Eligibility required a facial involvement of at least 0.5 % body surface area with an F‑VASI score ≥ 0.5, or ≥ 3 % BSA on non‑facial areas with a T‑VASI score between 3 and 60. Both male and female subjects were included, and the population encompassed individuals classified as vulnerable under regulatory definitions. No additional lifestyle restrictions were specified in the provided information.

The study is a multicenter, randomized, double-blind, placebo-controlled, dose-ranging Phase IIb trial evaluating subcutaneous GIA632 versus matching placebo in adult participants with non‑segmental vitiligo. After obtaining informed consent, a screening visit confirms eligibility criteria, including disease extent and baseline scoring. Eligible participants are then randomized at the baseline visit and receive the assigned study product. Follow‑up visits are scheduled at weeks 4, 12, 24, 36, and 48 to assess facial and total Vitiligo Area Scoring Index scores, achievement of predefined response thresholds, and safety parameters, including treatment‑emergent adverse events. The end‑of‑study visit occurs at week 48, concluding approximately 48 weeks of participant involvement plus the initial screening period. Early termination may be initiated for serious adverse events, significant protocol deviations, or participant withdrawal of consent.

The investigational product GIA632 is supplied as a solution for injection intended for subcutaneous injection. The assigned dose is 00 DF dosage form per administration. The dosing schedule and frequency are defined in the study protocol and administered by qualified personnel. Participants receive the product according to the randomized allocation and dosing regimen.

The control arm utilizes a matching placebo that contains no active substance. The placebo is presented in an identical appearance to maintain blinding. It is administered by the same route and schedule as the investigational product.

Drug administration is performed at study sites under direct observation. Compliance is assessed through injection logs and study visit assessments. All administrations follow the double‑blind, randomized design.

The primary efficacy assessment is the percentage change from baseline to Week 24 in the Facial Vitiligo Area Scoring Index (F-VASI) score. Baseline and Week 24 assessments are performed using the validated F‑VASI instrument, and the change is calculated as a percent difference relative to the baseline value. Comparative analysis will evaluate the dose‑response relationship of GIA632 versus placebo.

Secondary efficacy evaluations include:

• Achievement of ≥75% improvement from baseline in F-VASI (F‑VASI75) at Week 24.
• Percentage change from baseline to Week 24 in the Total Vitiligo Area Scoring Index (T-VASI) score.
• Achievement of ≥50% improvement from baseline in T-VASI (T‑VASI50) at Week 24.
• Achievement of F‑VASI50, F‑VASI75, and F‑VASI90 at Weeks 12, 24, 36, and 48.
• Achievement of T‑VASI50, T‑VASI75, and T‑VASI90 at Weeks 12, 24, 36, and 48.
• Achievement of a Vitiligo Noticeability Scale (VNS) score of 4 or 5 at Weeks 12, 24, 36, and 48.
• Recording of treatment‑emergent adverse events and serious adverse events.

All efficacy parameters are collected at scheduled study visits corresponding to baseline, Week 12, Week 24, Week 36, and Week 48. Data are analyzed using appropriate statistical methods to compare each GIA632 dose group with placebo and to characterize the dose‑response relationship.